Protection relays

Voltage, current, ground & insulation fault detection relays



Protection relays are often the last barrier to protect rolling stock and trackside equipment in the event of upstream protection system failure. They do not require auxiliary supply. Their mechanical life of 100 million operations exceed train life.
Protection relays are designed on an electromechanical technology providing high reliability with friction free mobile armature and maintenance free. It has a strong ability to withstand high overloads due to its magnetic materials. It is equipped as standard with weld-no-transfer contacts (1N/O+1N/C) for safety critical applications.


Protection relays are used in voltage catenary detection to protect power equipment from overheating both on board or trackside:
  • 3 phase AC voltage monitoring for low voltage or phase loss
  • over current and under current detection
  • battery charging current
  • electromagnetic brake failure
  • heat tracing cable surveillance (trackside)

Ground fault from chassis to ground for trackside or differential current relay is used to detect current leakage by comparing incoming and outgoing power
traction circuit lines or current unbalance in the brake system.

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Railway rolling stock
Railway signalling